1. Field of the Invention
The present invention relates to an optical disc reproducing method capable of reproducing a non-finalized optical disc, and particularly to an optical disc reproducing method capable of reproducing a non-finalized DVD+R standard optical disc (hereinafter referred to as a non-finalized DVD+R).
2. Description of the Related Art
In addition to optical discs based on various DVD standards defined by the DVD Forum, there is an optical disc based on the DVD+R standard defined by the DVD+RW alliance. In the Live File System of Windows Vista (Windows is the registered trademark of Microsoft Corporation) which is Microsoft Corporation's operating system for personal computer, it is default to use UDF (Universal Disc Format) 2.01. When data such as video or audio content is recorded on a DVD+R standard optical disc in the Live File System of Windows Vista, the optical disc is not finalized, but becomes a non-finalized DVD+R.
Data is recorded on a DVD+R standard optical disc in a multi-session data structure. When the non-finalized DVD+R on which one or plural sessions are recorded is reproduced, it is necessary to read data called ICB (Information Control Block) in a closure positioned at the outermost circumference of the recorded area. A VAT (Virtual Allocation Table) based on the UDF is recorded in the recorded area. Since the ICB includes information indicating where the VAT is recorded, the VAT can be read by reading the ICB. When the VAT is read, the session structure can be known, and the optical disc reproducing apparatus can obtain information necessary for reproducing the non-finalized DVD+R.
As related arts, Japanese Unexamined Patent Publication 2005-149646 and Japanese Unexamined Patent Publication 2007-323753 are known.
In the DVD+R standard optical disc, the number of sectors (the number of tracks) assigned as the closure is small. Thus, when an optical pickup moves from an inner circumferential side of the optical disc to an outer circumferential side to read the ICB in the closure in order to reproduce the non-finalized DVD+R, there occurs a case where the optical pickup moves onto a non-recorded area positioned outside the closure. In this case, there occurs an out-of-focus state in which the laser beam is out of focus on the non-recorded area.
As stated above, in the related art optical disc reproducing apparatus, when the non-finalized DVD+R is reproduced, it is difficult to accurately position the optical pickup in the closure having a small number of tracks, and there is a problem that the non-finalized DVD+R can not be reproduced. This problem arises notably in, for example, an in-vehicle reproduction-only optical disc reproducing apparatus. As stated above, when data is recorded on the DVD+R standard optical disc in the Live File System of Windows Vista, the non-finalized DVD+R is produced, and therefore, it is desired to enable the non-finalized DVD+R to be reproduced.